1. Field of the Invention
Hermetic refrigerant compressors provided with means for cooling the lubricant to maintain high efficiency and long operating life for the compressor drive motor.
2. Description of the Prior Art
U.S. Pat. No. 2,854,594 discloses a motor containing an enclosed lubricating system wherein the temperature of the lubricant is reduced through heat exchange with the motor casing, the latter including cooling fins or ribs. The disclosure in this patent fails to suggest this feature in combination with a refrigerant compressor nor the specific means for handling a refrigerant and lubricant mixture.
U.S. Pat. No. 3,408,827 is directed to a screw compressor in which a mixture of refrigerant and oil is directed on the motor for cooling purposes. Centrifugal action imparted by the motor on the mixture is operable to separate a substantial portion of the oil which is directed to an oil sump or cooler. This patent fails to disclose the concept of using a portion of the casing wall for heat exchange and requires a separate oil cooler which the present invention seeks to avoid.
U.S. Pat. No. 3,663,127 discloses a hermetic compressor and cooling system for the motor therein. The lubricating oil is directed against the motor windings by means of an oil pump disposed in the lower portion of the compressor shell. The oil then flows downwardly along the inside surface of the casing walls in returning to the sump. Any lubricant coming into contact with the walls is on a somewhat random basis in that there are no means provided for specifically directing the refrigerant-lubricating oil mixture to this area.
U.S. Pat. No. 3,833,318 describes a rotary compressor in which the incoming oil is subjected to an abrupt change in direction to aid in separating the oil from the refrigerant. While some oil will inherently flow against the inside walls of the casing, there is no suggestion that this is effective in any way to cool the same.
U.S. Pat. No. 2,979,917 provides a cooling system for a hermetic compressor which includes a de-superheating coil. Discharge gas is caused to flow through the coil and into the chamber in which the drive motor is located. This, of course, necessitates a separate coil which is avoided by the present invention.
U.S. Pat. No. 3,727,420 also provides a de-superheating coil and is similar in many respects to the aforementioned U.S. Pat. No. 2,979,917.
U.S. Pat. No. 2,492,611 shows a hermetic compressor in which an oil cooling system is provided with a line conducting oil collected in a sump to the upper portion of the shell. The oil is sprayed against the upper surface of the shell and flows down along the inside wall where it is cooled by contact therewith.
U.S. Pat. No. 3,922,114 is directed to a screw compressor which uses discharge gas and entrained oil to cool the motor. The mixture of gas and oil is directed against the walls of the shell to induce separation.